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Se describieron las características morfológicas de los granos de polen de cinco especies pertenecientes a la familia Cactaceae, subfamilia Cactoideae: Tres especies, Echinopsis chalaensis (Rauh & Backeb.) Friedrich & G.D. Rowley, Haageocereus decumbens (Vaupel) Backeb. y Pygmaeocereus sp. Johnson & Backeb., (tribu Trichocereeae); Corryocactus brevistylus (K. Schum. ex Vaupel) Britton & Rose (tribu Pachycereeae) y Neoraimondia arequipensis (Meyen) Backeb. (tribu Browningieae). Todos los granos de polen fueron observados con microscopio óptico (MO), estos se presentaron en mónadas, la forma varió de esferoidal a oblato esferoidal, siendo todos colpados, excepto C. brevistylus, con espínulas que van desde menos de 1 µm hasta los 2 µm, el grosor de la exina varía entre 2 y 3 µm, no se aprecian mucha diferencia del tectum, el cual siempre es perforado. Se presenta una clave para di...

The accumulation of nitrogen (-N) is a serious problem in aquaculture as it could lead to mass mortality events of the cultivated species. Chemilitotrophic nitrification is the most recognized in nitrogen removal underestimating the role of heterotrophic nitrifiers. In the present study, the heterotrophic nitrification capacity of 8 bacterial strains isolated from mangrove soil, periphyton and biofilters was evaluated. The strains were grown in heterotrophic nitrification base medium (HNM medium) with three different nitrogen sources, ammonium, nitrite or nitrate at a final concentration of 8 mg L-1, 5 mg L-1 and 80 mg L-1 respectively. The concentration of nitrogen (-N) and OD (600 nm) were determined periodically. Only in 4 strains belonging to the Bacillus genus was the capacity for heterotrophic nitrification and aerobic denitrification observed. Among these strains, SM4 strain prese...